[kwlug-disc] Bundling HD's. LVM vs mdadm vs ???

William Park opengeometry at yahoo.ca
Thu Apr 11 19:59:50 EDT 2013


On Thu, Apr 11, 2013 at 09:01:39AM -0400, unsolicited wrote:
> I'm running out of backup space, so I'm probably going to buy a
> larger drive, and move a current drive into another computer -
> expecting to bundle it with the drive already there into a single
> logical presentation. (Add 4TB, move 2TB -> 2TB + 2TB = 4TB.)
> 
> I don't 'do' RAID (at least at home, where high availability isn't
> an issue), and mistrust striping - lose 1 drive, both be gone. I
> prefer to say 'this' amount of space for 'this' purpose, so when I
> run out of space I'm aware of and address the issue.
> 
> (Presumably a worst case scenario for such bundling upon failure is
> losing one file - the one that crosses physical drives. Correct,
> even today?)
> 
> I've known for some time LVM is out there, just never needed it.
> There's also mdadm ('LINEAR') [Which I gather LVM calls upon.]
> 
> Any particular pros / cons / preferences / suggestions / thoughts
> for bundling multiple drives into a single logical drive?

If you want 2TB + 2TB = 4TB, then there are several options:

    1. mdadm (raid0) -- it appears as /dev/md0, so you put whatever
    filesystem on top.
    2. btrfs -- slooow compared to raid+ext4 

Either solution has the same problem... lose 1 disk, you lose the entire
filesystem.
-- 
William



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